What are Trans Fats & Why Are Trans Fats Bad For Your Health?
What is a Trans Fatty Acid?
Trans fats are fats that contain damaged unsaturated fatty acids. The double bonded carbons in a trans fatty acid have been flipped from the naturally occurring ‘cis’ form into an un-natural trans form. Why are trans fats bad? Trans fats are bad because of this difference in the trans fats chemical structure compared with the naturally occurring ‘cis’ fat structure. The trans fatty acid has a different geometry and this altered geometry has important biological implications.
Normally in a natural fatty acid, wherever there is a double bond in the otherwise long straight carbon chain of a naturally occurring fatty acid, there is a crimp in the chain. This is because the cabon atoms in the double bond are aligned in the ‘cis’ configuration. In biological systems, fatty acid double bonds are always present in the ‘cis’ configuration. The biological system needs the double bond to cause a crimp (or a bend) in the carbon chain for particular purposes. Yet the ‘cis’ configuration of a carbon double bond is one of two possible configurations that this double bond could assume. The other possible configuration that the bond could take is called the ‘trans’ configuration. Trans configured fatty acid double carbon bonds are never created in a biological system.
A fatty acid with a ‘trans’ configured double bond in the carbon chain looks and acts differently than its ‘cis’ counterpart. While ‘Cis’ double carbon bonds curl the carbon chain around the bond, bending the carbon chain back upon itself at the location of the double bond. Trans double carbon bonds simply add a zig-zag to the carbon chain, effectively straightening out the chain at the trans double bond location. The answer to the question “why are trans fats bad” can be found in the fact that biological systems, firstly, at the cellular level, simply do not have the enzymatic means to utilize fatty acids that exist in this form. In fact, trans configured double bonds in fatty acids chains pose a serious burden upon the enzymatic systems that deal with fatty acids in and around the cells.
Why Are Trans Fats Bad
To answer the question “why are trans fats bad?” you have to look at what happens to a trans fatty acid once it encounters a cell membrane. On the cell membrane there are many, many different enzymes. Some of these enzymes are purposed to manipulate fatty acids. There are numerous uses for fatty acids by cells, and enzymes located on the cell membranes carry out the chemical transformations that the fatty acids may undergo.
Every time an enzyme which is purposed to deal with fatty acid carbon chains encounters a trans double bond in the fatty acid carbon chain, that enzyme locks onto that trans carbon double bond but can not complete its action. Enzymes are geometrically specific. They are complex molecules that can carry out their “designed” function only on substrates which have the correct special orientation. In a manner similar to the matching of a key to a lock, enzymes must match their substrate in order to complete their actions. Since a trans configured double bond in a fatty acid never occurs naturally in a biological system the enzymes that must deal with fatty acid double bonded carbons can not match nor manipulate these fatty acids. The worst thing about this is that there is no way for an enzyme thus engaged to release the trans fatty acid. It simply never works again. A new enzyme must be manufactured to take its place. And, so it goes. When the next trans fatty acid to come along and encounters the new replacement enzyme, the same thing happens again. The more trans fats a person consumes in his diet, the greater is the enzymatic drain that these damaging fatty acids bring about.
The other reason that a trans fatty acid may have a damaging effect upon your cells is because a trans fatty acid behaves much like a saturated fatty acid does. If such a fatty acid should eventually become incorporated into a cellular membrane (if this is even possible at all) it would behave much like a saturated fatty acid would behave, imparting stiffness, and inflexibility to the membrane since it it is long and straight just as a saturated fatty acid is.
References:
Murray, T. N.D. and Jade Beutler, R.R.T., R.C.P.,(1996). Understanding Fats & Oils, Progressive Health Publishing, Encinitas, CA.
Gordon, Garry, M.D., D.O., M.D.(H.), Herb Joiner-Bey, N.D.(2004).The Omega-3 Miracle. Freedom Press, Topanga, CA
This post is part of the series: Good Fats and Bad Fats
Fats are among the least understood of the nutritive elements. Certain fats contain essential fatty acids but the Western diet fails to provided adequate and balanced amounts of these. Bad fats are all too prevalent in the Western diet and these fats yield damaging effects upon health.